Re: [foxboro] OM dqchange value status


Alex:

Thanks again for the useful information.  I have used your macros to make
the program much more robust and informative.

I understand about the OM reconnection task and have obviously seen it in
action over the years.  ;-)  I'm not sure why our existing program seems to
stop updating once a station has gone offline.  Unfortunately for me I
don't have a working test bed to test this scenario, but now I have some
better tools in place to hopefully track down what is happening/has
happened the next time.

On a side note, while migrating to Solaris 8 and Sun Studio 11, the OM
value structure defined in the file om_udat.h causes errors.  It appears
that the term "value" is now a key or reserved word.  I have modified the
om_udat.h file to change the value structure references to fox_value.


Steve



foxboro-bounce@xxxxxxxxxxxxx wrote on 03/13/2009 06:27:18 PM:

> Re: One question still remains for me, though, and that has to do with
> re-establishing the connections.  I understand that the program will be
> notified of the remote OM server dies, but will it also be notified if
> the remote OM server again becomes available?
>
> Yes. When the station reboots or otherwise becomes reconnected, it
> issues a multicast announcing that the compounds are now available. This
> triggers the OM reconnection task. Once reconnection is complete, the
> status bits update and you get a change.
>
> You can see this with DM/FV. Call up a display. Disconnect the WP from
> the control network. See it smurf. Reconnect to the network. See the
> values come back.
>
> CPs also issue the reconnect message when they checkpoint. Since the
> reconnect message is a multicast, it could get lost - say if the input
> buffer is full on the WP - so the checkpoint should clear any
> stragglers.
>
> Does this help?
>
> Regards,
>
> Alex Johnson
> Invensys Process Systems
> 10900 Equity Drive
> Houston, TX 77041
> 713 329 8472 (desk)
> 713 329 1600 (operator)
> 713 329 1944 (SSC Fax)
> 713 329 1700 (Central Fax)
> alex.johnson@xxxxxxxxxxxxxxxx

 
 
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